Mechanical assistants with embedded CAN networks

Service robots are revolutionizing the agricultural sector. They sow, weed, fertilize, and feed animals with increasing autonomy.

Cindy Weissmueller

10/03/2014

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For farmers the day usually starts at 3 or 4 a.m. They have to look after their cattle, feeding and milking them. Until now: Thanks to a milking robot, the cows milk and feed themselves.

This means a more comfortable life for farmers. They are able to go back to bed on a rainy day or can do other things (such as cooking dinner) or can manage other tasks, because the cows now decide when it's milking time. Machines don't complain about getting up early. The robots feed and milk the cows without the help of a human; no one has to move the cows into the milking box. The animals go there on their own because they know there is food, a measured amount of grain in the box.

Robotics in agriculture

Service robots are revolutionizing the agricultural sector. They sow, weed, fertilize, and feed animals with increasing autonomy. Netherlands-based company Lely, a manufacturer of robot milking systems, offers products, from stall cleaning systems to automatic feeding systems, among them the Lely Astronaut A4 milking robot including a mechanical arm, teat-cleaning equipment, and CAN network communications. According to Lely, an increase in labor productivity is desired to ensure a healthy dairy business in the future. Achieving more liters of milk per worker in an animal-friendly way is the company's goal. They think only one person can milk 2 million liters per year. On conventional dairy farms where milking is done twice a day now, production increases of 10% to 15% can be achieved with a milking robot, which handles about 180 milkings per day.

A robotic milking system is highly reliable, offering capabilities 24/7, except for maintenance. It is trained to prepare the cow for milking, to attach the teat cups and to reattach them if required, to detach after milking, and to carry out post-treatment. Due to the robotic milking system, many factors can be monitored for each individual cow, factors that cannot be provided in a conventionally milked herd. With robots, milking decisions are transferred from the farmer to the cow. It is all about early signals. Owners can treat cows individually again, which results in improved health of the cows, shorter calving intervals, and reduction of feed costs.

In the so-called cow traffic, the cow decides when she wants to eat, get milked or lie down, thereby improving the well-being of the cow. This influences the cow's behavior when it comes to visiting the robot. Robotic milking is different from conventional milking in many ways. One of the main differences is that cows can be milked more in tune with their natural behavior. This makes the process easier for the cow, which shortens the learning curve, increases the throughput, and, as a result, the capacity of the robot.

Lyndon Williams, a farmer from Wales, U.K., said: "There was one cow we always needed to bring to the robot. But now — with the more open entrance of the Astronaut A4 robot — even this cow regularly visits voluntarily. She even comes too often!"

The robot arm remains underneath the cow and controls the entire milking process. With almost all sensors housed in the arm, measurement is done close to the udder, which improves accuracy. Attachment speed and accuracy is a crucial factor for the capacity of the robot. When a cow goes into the box, the stainless-steel robotic arm moves under the cow, scans it with lasers to find the teats, and attaches four teat cups. The teat detection system (TDS) of the company features a three-level scanning technology, to find the teats. Above the cow is a mounted video camera that measures the animal's position, which means if the cow moves, the robotic arm moves with her.

The MQC (Milk Quality Control) is a tool for measuring milk quality. It is located inside the arm of the robot just beside the udder. During milking, the milk is continuously monitored per quart. This provides the user with vital information on mastitis, fat and protein, and lactose for managing milk quality and the cow's health. Mastitis is the inflammation of breast tissue. To prevent it, the optional MQC-C somatic cell count (SCC) measurement system monitors the SCC per milking per cow. Alarming deviations are noticed and reported. The Milk Quality Control - Somatic Cell Count Indicator (MQC-C) is an optional part of the milking robot and is used to measure the class of the somatic cell count. This is done in an automated process and can be set in Lely's management system called T4C (time for cows) to carry out the test per cow, group of cows, or the whole herd. The test is based on the drain time of a mixture of the milk and Astri-Cell (a fluid needed for measuring the somatic cell count in the milk). The test also indicates the udder health. The MQC-C gets its input (when to test) from the MQC and sends its output (test results, number of visitations) to the MQC. Results and class attentions of the test can be found in the T4C software. Hardware-related alarm messages can be found on the X-Link. The visitation lists generated by T4C can be found on the X-Link. The MQC-C can be built into the Astronaut A3 ex-factory but also installed on an existing Astronaut A3 milking robot. Depending on the production date, it is possible some other modifications must be done to install the MQC-C on existing milking robots. It has three primary parts: the sampler, the processor and the wall socket.

The sampler is installed on the support between the MQC and the milk jar. The function of the sampler is to separate a small quantity of the milk for the test when a test must be done. The sampler gets input from the processor and sends output to it. The processor is a box (a base and a cover) with pumps, valves, chambers and electronics. It is installed on the milking robot frame behind the intermediate panel and is attached to the processor installation bracket. The processor has three main functions: to transport, mix, test, and drain the mixture. The processor pumps the milk from the sampler to the processor and adds Astri-Cell to the milk. When the test is done, the processor pumps the mixture to the sewer. The processor gets its input from the sampler (electronic and milk samples), the wall socket (Astri-Cell, water and compressed air), and the MQC (via the CAN connector). The processor sends output to the sampler and the MQC. The wall socket is installed behind the intermediate panel on the right side of the machine room above the pumps. The wall socket joins the input of the water, Astri-Cell, and compressed air supply with the tube bundle that leads to the processor. It is provided with pressure reducers for the water and the air supply.

Cost savings increase over time. It is not just the initial investment that counts, but all costs in the years to come. The company says the system only requires a maximum of four maintenance calls per year, and because there is no need for floor cleaning (as milk cups cannot drop to the floor and udders are brushed instead washed), the system doesn't waste any water.

Saving energy also decreases costs. Only a few movements are needed for the connection and removal of teat cups. Only one pneumatic system is needed for all milking robots and related equipment in the barn, such as selection gates.

Jean-Philippe Côté, a farmer from Canada, said "the efficiency of production costs such as water, soap, electricity and feed is excellent."

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Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. Featured articles in this digital report compare PLCs and programmable automation controllers (PACs), industrial PCs, and robotic controllers.